Composite solid electrolytes (CSEs) combining the advantages of both inorganic and organic solid-state electrolytes, are expected to become the most promising solid electrolyte owning to their favorable interfaces with electrodes. However, low room-temperature ionic conductivity restricts the application of CSEs in lithium metal batteries. Herein, we design an intercalated CSE based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). Kaolin (2SiO2-Al2O3-2H2O), employed as an oxidative flame retardant, imparts nonflammability to the material. The polar molecule dimethyl sulfoxide (DMSO) is inserted between the kaolin layers as the pre-intercalation treatment, serving as an organic additive within the PVDF-HFP based SPE. The intercalated structure of CSE provides rapid Li+ transport channels, resulting in a high ionic conductivity (8.58 × 10−4 S cm−1) and large Li+ transference number at room temperature. The Li||Li symmetrical cell with prepared CSE exhibits outstanding
Solid polymer electrolytes (SPEs) are one of the most promising alternatives to flammable liquid electrolytes for building safe Li metal batteries. Nevertheless, the poor ionic conductivity at room temperature (RT) and low resistance to Li dendrites seriously hinder the commercialization of SPEs. Herein, we design a bifunctional flame retardant SPE by combining hydroxyapatite (HAP) nanomaterials with N-methyl pyrrolidone (NMP) in the PVDF-HFP matrix. The addition of HAP generates a hydrogen bond network with the PVDF-HFP matrix and cooperates with NMP to facilitate the dissociation of LiTFSI in the PVDF-HFP matrix. Consequently, the prepared SPE demonstrates superior ionic conductivity at RT, excellent fireproof properties, and strong resistance to Li dendrites. The assembled Li symmetric cell with prepared SPE exhibits a stable cycling performance of over 1200 h at 0.2 mA cm−2, and the solid-state LiFePO4||Li cell shows excellent capacity retention of 85.3% over 600 cycles at 0.5 C.